Stabilizing fins are primarily used on a watercraft such as sail boats or any similar water going vessels which use a fin or keel and water sports boards such as surfboards, wind-surf boards, kite-surf boards, stand up paddle boards, wake boards and the like. Generally, surf boards, windsurf boards, SUP boards, wake boards and kite surfing boards have a fin or multiple fins attached to their bottoms that enable steering of the board and the ability to counteract the lateral force that tends to move the board in a lateral direction due to the direction of moving of the board on a wave.
In sail boats the main purpose of the keel is to counteract the force of the wind. On sail boats, the wind provides a force which enables the sail boat to move in its desired direction. The force which is caused by the wind is a lateral force which tends to tip the sailing boat.
When it is at rest, a watercraft's weight is borne entirely by the buoyant force of the watercraft. At low speeds generally the watercraft hull (or body, board, etc.) acts as a displacement hull, meaning that the buoyant force is mainly responsible for supporting the watercraft. As speed increases through the water, the shape of the hull causes hydrodynamic lift to increase as well. At some speed, hydrodynamic lift becomes the predominant upward force on the hull and the craft is “planing”. Planing decreases drag on the body of the watercraft and allows for increased speed of the watercraft.
Standard fin structures for use in watercraft such as water sports boards generally have one or more single solid fin structures (i.e. not having any openings for the water to flow through) extending from the bottom of the watercraft into the water. Current standard fin structures generally extend along a vertical axis of symmetry and have a symmetrical profile across that axis. Standard fin structures can vary by having different depths, rake angles (extending in the direction of water flow), surface area and cross-section profiles that all depend on the purpose of the board and operating conditions and desired performance characteristics.
In the case of standard fin shapes, when moving through the water, water is flowing in the direction from the leading edge of the fin towards the trailing edge of the fin. In the vicinity of the fin, the water flow deflects and follows the shape of the fin. On each side of the fin, the local water velocity is increased relative to the hull which causes a pressure differential and lateral force is generated and acting on the surface of the fin, perpendicular to the axis of symmetry and direction of water flow. Because the cross section of standard fins have a symmetrical hydrodynamic profile, the lateral force is generated equally on the two opposing sides and act against each-other thereby giving lateral stability to the hull. Because the fin is moving through water, resistance force which occurs acting in the direction the water is flowing, causing what is commonly referred to as fin drag. In addition, because of the symmetric profile of the fin structure, no significant longitudinal force (hydrodynamic lift) is generated to counteract the force of gravity pushing the board into the water therefore does not get the board on plane more easily.
What is desired is a fin structure that provides lateral stability and generates hydrodynamic lift allowing the watercraft to get on plane more easily.
It is with respect to these and other considerations that the disclosure made herein is presented.